In the related art, a vehicular power back door automatic opening and closing system disclosed in JP-2005-307692A (Reference 1) and a control apparatus and a method disclosed in JP-2009-18655A (Reference 2) are known as vehicular operation detecting apparatuses.
According to Reference 1, a user's motion of touching a capacitive sensor, which is installed in a vehicle, with a part (a finger or the like) of the body is a motion to demand the opening and closing of a back door. Specifically, the sensor includes two touch sensors. For example, the direction of a demanded operation of the back door is determined based on a sequence (time difference) in which the user touches the two touch sensors.
Similarly, according to Reference 2, an operation performed by a user such as brining various objects close to or moving various objects away from a predetermined location is detected (determined), and various functions of a vehicle are enabled in accordance with a detection result.
According to Reference 1, based on a magnitude relationship between a capacitance-related pulse signal generated and output by each touch sensor and a predetermined threshold value, it is determined whether a human's (user's) motion occurs. Accordingly, a sequence in which the user touches the two touch sensors is determined by a timing when the magnitude relationship between the pulse signals of both the touch sensors and the predetermined threshold value is inversed. If there is a variation in sensitivity between both the touch sensors due to effects of product tolerances or environmental changes, that is, if the sensitivities of both the touch sensors are not equal to each other, there is a possibility of erroneously determining the aforementioned sequence. This also applies to Reference 2. Hereinafter, this will be specifically described.
FIG. 15 illustrates a state in which a user moves a part (finger H or the like) of the body along a direction in which sensor electrodes 91, 92, and 93 of three touch sensors are provided side by side in the listed sequence. In FIGS. 16A to 16C, progressions of detection signals S91, S92, and S93, which correspond to pulse signals and are generated and output by the sensor electrodes 91 to 93 in accordance with a user's motion, are illustrated together with a threshold value Sth for determination of a magnitude relationship therebetween.
As illustrated in FIG. 16A, if sensitivities of the sensor electrodes 91 to 93 are equal to each other, waveforms of the detection signals S91 to S93 are the same, and the detection signals S91 to S93 are generated in the listed sequence in accordance with the user's motion. Accordingly, time differences occur such that times (so-called threshold value off timings) t91, t92, and t93 when the detection signals S91 to S93 go below the threshold value Sth also occur in the sequence of the sensor electrodes 91 to 93. In other words, a user's motion (the direction of movement of the user's finger H) is determined by monitoring the sequence of the times t91, t92, and t93.
In contrast, as illustrated in FIG. 16B, even if the sensitivities of the sensor electrodes 91 to 93 are decreased in the listed sequence, similarly, detection signals S94, S95, and S96 are generated in the listed sequence in accordance with a user's motion. In contrast, the detection signals S94, S95, and S96 of the sensor electrodes 91 to 93 having relatively high sensitivities are generated in such a way as to contain the detection signals S94 to S96 of the sensor electrodes 91 to 93 having relatively low sensitivities. In this case, time differences occur such that the sequence of times t94, t95, and t96 when the detection signals S94 to S96 go below the threshold value Sth is inverse to the original sequence of the sensor electrodes 91 to 93. Accordingly, it is determined that a user's motion (the direction of movement of the user's finger H) is reversed to the original user's motion.
Alternatively, as illustrated in FIG. 16C, if the sensitivity of only the sensor electrode 92 is higher than those of the sensor electrodes 91 and 93, regardless of a user's motion, a detection signal S98 of the sensor electrode 92 is generated to contain detection signals S97 and S99 of the other sensor electrodes 91 and 93. In this case, among the times t97, t98, and t99 when the detection signals S97 to S99 go below the threshold value Sth, the time t99 is ahead of the time t98, and thus, the user's motion (the direction of movement of the user's finger H) cannot be determined.
Even if sensitivities of both touch sensors are equal to each other, since separation distances between a moving human (user) and both the touch sensors are not constant in a state where there is no contact between the moving man and both the touch sensors, there is the possibility of erroneously determining the aforementioned sequence. Hereinafter, more detailed description will be given.
FIG. 17A illustrates a state in which a user moves a part (for example, the finger H) of the body along one direction in which sensor electrodes 101 and 102 of two touch sensors are provided side by side in the listed sequence, while the posture of the part of the body is parallel to the one direction. In FIG. 17B, progressions of detection signals S101 and S102, which are generated and output by the sensor electrodes 101 and 102 in accordance with a user's motion, are illustrated together with the threshold value Sth for determination of a magnitude relationship therebetween.
As being apparent from the drawings, in this case, waveforms of the detection signals S101 and S102 are the same, and the detection signals S101 and S102 are generated in the listed sequence in accordance with the user's motion. Accordingly, time differences occur such that times t101 and t102 when the detection signals S101 and S102 go below the threshold value Sth also occur in the sequence of the sensor electrodes 101 and 102. As described above, a user's motion (the direction of movement of the user's finger H) is determined by monitoring the sequence of the times t101 and t102.
In contrast, FIG. 18A illustrates a state in which a user brings a part (for example, the finger H) of the body close to two sensor electrodes 101 and 102 while the posture of the part of the body is inclined with respect to the aforementioned one direction, and then moves the part of the body away from the two sensor electrodes 101 and 102 (that is, a state in which the part of the body is not moved in the one direction and a direction opposite thereto). In FIG. 18B, progressions of detection signals S103 and S104, which are generated and output by the sensor electrodes 101 and 102 in accordance with a user's motion, are illustrated together with the threshold value Sth for determination of a magnitude relationship therebetween.
As being apparent from the drawings, in this case, the detection signals S103 and S104 are generated such that the detection signal S103 of the sensor electrode 101 having a relatively short separation distance from the user (the finger H) is higher than the detection signal S104 of the sensor electrode 102 having a long separation distance, and contains the detection signal S104. In this case, time differences occur such that, between times t103 and t104 when the detection signals S103 and S104 go below the threshold value Sth, the time t104 is ahead of the time t103. Accordingly, a motion (movement of the finger H in the direction opposite to the one direction) different from an actual user's motion is determined (erroneous determination).